Occlusive or mural thrombi that are associated with fissured atherosclerotic plaques are the most common cause of acute myocardial infarction, sudden cardiac death and unstable angina. Angiographically mild coronary lesions have been shown to progress to severe or total occlusion secondary to plaque rupture and thrombosis and may account for up to two thirds of patients with unstable angina and myocardial infarction. Since plaque rupture is a critical determinant of clinical consequences regardless of the extent or degree of interference with the flow, the ability to identify lesions predisposed to rupture is of utmost importance. In this project we will develop a computer software for the identification and ranking of the severity of arterial lesions. The software will work in conjunction with intravascular ultrasound systems. In Phase I we have developed a prototype of this software. In Phase II a production version of the software will be developed. An animal model study and a pilot clinical study are planned in the Phase II work to evaluate the software and prepare it for clinical study in Phase III. PROPOSED COMMERCIAL APPLICATION: Due to the spread of coronary heart disease, it presently causes from one third to one half of all deaths of people between the ages of 35 and 64 years in the United States, the availability of tools for early diagnosis is important. The proposed technology can identify lesions that are not angiographically severe, but are structurally unstable, which is currently not possible with any of the existing diagnostic tools.